Medical compression garments (abbreviated by MCG) are garments which are mainly made of elastic knitted fabric. Their aim is to provide a pressure or compressive force, respectively, to a human skin, especially to a limp such as an arm or a leg, for e.g. the treatment of venous diseases and lymphatic disorders. The patients are usually required to apply some form of orthese during an entire day for a long period of their lifetime and therefore it is desirable to provide an orthese in form of a garment. Patients are generally more compliant with wearing the medical compression garment if it is comfortable to wear. Medical compression garments can for example be used to compress a leg below the knee, an entire leg, an arm, a hand and so on. They can be designed in the form of stockings, socks, panties, sleeves, gloves, etc.
Medical compression garments are usually classified by size and compression strength and must comply with normative specifications in some countries such as the German norm RAL-GZ 387 or the French norms NF G 30-102b. These norms impose technical requirements for ensuring the medical effect of a medical compression garment. Criteria to be checked are the used materials and the physical performance of the medical compression garment. The requirements imposed on the manufacture of the fabric, of which the medical compression garment consists, concern the combination of so called inlaid yarns with so called loop yarns. Today the type of knitting machines which can be used to manufacture medical compression garments that fulfil the norm requirements is limited.
Depending on the knitting pattern different appearances and functional effects can be obtained. The functional effect determines if a patient complies with the necessity to wear an orthese in form of a medical compression garment. FIGS. 1 to 10 show examples of known knitting patterns or stitch patterns, respectively, for fabrics which are used for medical compression garments. The displayed stitch patterns can be produced with available types of knitting machines.
FIGS. 1 and 2 show the so called plain stitch pattern. Two yarns 1 and 2 are used, one yarn being the so called inlaid yarn and the other yarn being the so called loop yarn 2. At the crossing point of an inlaid yarn 1 and a loop yarn 2 there are two possibilities of yarn combinations that determine the state of the particular stitch defined by the crossing point. When the loop yarn 2 is in front of the inlaid yarn 1 (referring to the fabrics outside, i.e. the side/surface opposite to the side/surface looked at in the figures), then the stitch defined by the crossing point has the state “on”. When the loop yarn 2 is located behind the inlaid yarn 1, then the stitch has the state “off”. A pattern in which the states of horizontally and vertically consecutive stitches are assigned the states “on” or “off” is called stitch pattern. FIG. 2 shows a diagram of a plain stitch pattern wherein each stitch that has the state “on” is represented by a black rectangle and each stitch that has the state “off” is represented by a white rectangle.
FIG. 3 displays the known rib 1/1 stitch pattern. FIG. 4 shows the corresponding diagram with stitches having the state “on” as black rectangles and stitches having the state “off” as white rectangles. A fabric with the rib 1/1 pattern consists of alternating columns of stitches having either the state “on” or the state “off”.
FIG. 5 shows the known rib 1/2 stitch pattern and FIG. 6 shows the respective diagram with rectangles whose colour depends on the state of the corresponding stitch. The rib 1/2 stitch pattern is characterised by a column of stitches having the state “off” that is followed by two columns of stitches having the state “on” which are in turn followed by a column of stitches having the state “off”.
FIG. 7 shows the known rib 1/3 stitch pattern and FIG. 8 shows the corresponding diagram. Inbetween two parts of a fabric each consisting of three columns of stitches in the state “on” there is one column of stitches having the state “off”.
FIGS. 9 and 10 show further examples of stitch patterns known in the state of the art. Theoretically, there are endless possibilities of stitch patterns providing certain visual effects, e.g. the Jacquard knitting, however the number of stitch patterns complying with the normative requirements is limited.
One of the important aspects for the provision of wear comfort is the thickness of the fabric. By employing the so called terry-loop pattern a bulky fabric with a certain thickness can be obtained which is comfortable to wear. The terry-loop pattern can, however, not be manufactured with the knitting machines which are currently used for manufacturing medical compression garments. These knitting machines have usually 20 to 32 needles per inch (787 to 1260 needles per meter) and a diameter of 3¾ to 6⅕ inch (95.25 millimetres to 157.48 millimetres). FIG. 11 displays a fabric with the terry-loop pattern. The bulky aspect of the terry-loop pattern is obtained by the so called terry yarn 20 which sticks out of the fabric by some extra length and is not held or retained by the ground yarn 10.
The known stitch patterns of medical compression garments displayed in FIGS. 1 to 10 may have bulky parts in the fabric when the loop yarn 2 is located in front of the inlaid yarn 1. Hence, a certain fabric thickness can be achieved if a stitch has the state “on”. As far as the plain stitch pattern shown in FIGS. 1 and 2 is concerned, the bulky aspect is, however, rather limited. The bulky aspect is increased when there are more than two horizontally consecutive stitches having the state “on”. This is the case for the stitch patterns displayed in FIGS. 5 to 8, wherein the rib 1/3 pattern has more bulky parts than the rib 1/2 pattern.
The rib patterns all lead to fabrics with ribs or parts form similar to a rib. Not all patients may want to wear medical compression garments consisting of fabrics with ribs. Furthermore, the provision of ribs, especially the provision of relatively wide ribs as being the case for the rib 1/3 pattern, may lead to structural instabilities of the fabric or the medical compression garment, respectively.
Patent document U.S. Pat. No. 4,332,150 discloses a fabric-producing machine in combination with a patterning system which implements a non-repeating pattern, wherein the patterning system comprises means for generating pattern-control signals randomly and pattern-limiting means that are operative for automatically imposing predetermined patterning restraints upon the pattern-control signals and for limiting the number of immediately consecutive joining identical stitches formed in a course. The produced fabric comprises courses and wales.